| dc.description.abstract | This study aims to modify Goddard Cumulus Ensemble microphysics (GCE) scheme,which is the widely used microphysics scheme for simulations and forecasts around the world, from single-moment to double-moment scheme. The upgraded scheme predicts the mixingratios of seven species hydrometeors (water vapor, cloud water, rain water, cloud ice, snow,graupel and hail), and total number concentrations of hydrometeors in warm-rain processes(cloud water and rain water). To examine the performance of GCE double-moment, it was evaluated and compared to different microphysics schemes by: 1) an idealized 2D thunderstorm, 2) an idealized 3D supercell storm tests and 3) a warm-rain processes dominant real case over Taiwan.
Similarities and differences of precipitation between GCESM and GCEDM examine by 2D idealized thunderstorm test. For the 3D supercell idealized test, the result of accumulated rainfall is less in GCE double-moment compared to GCE single-moment, but the features of the dynamic, thermodynamic, and rainfall rate are similar as GCE single-moment scheme. In addition, when calculating the total number concentration, GCE double-moment scheme shows the capability to present more diversity of rain droplet sizes in both convective and stratiform regions toward reality, and this is similar as other double-moment schemes. On the other hand, the performance of quantitative precipitation forecast showed that, the GCE double-moment scheme is had better forecast skill compared to the GCE single-moment, especially for the warm-rain processes dominant situation in heavy rainfall region. By appending rain number concentration forecast, accretion of cloud and rain as main rainwater source microphysics process becomes weaker. It leads to reduce overestimate of accumulated rainfall obviously. For dynamic, low level convergence in GCEDM is weaker than GCESM. Low level water vapor is hard to arrive high level by updraft. Therefore, lower saturation and more difficult to transform into hydrometeors. Finally, it makes precipitation decrease dramatically. In summary, GCEDM
not only provides more detail hydrometeor particle information, but also can get better benefit of forecast. | en_US |